whats the difference between working out an hour and a half once a day vs 45 min twice??

is there any what soever?

Why would you need to work out that long anyways? Personally I can hit the weights HARD in one 45-50 minute session. I don't rest an unnecessary amount between sets.

However, to answer your question...I don't really see a difference. If you insist on working out for that long, it might be better to break it up into two sessions...if only to let your body cool off for a bit.

two 45 minute work outs is better

It depends on when you are going to be doing this two workouts, if say you are going to wait in hour or so to do your second than it would most likely benifit you more just to do the one hour and a half workout. However if you are planning on working out for 45 in the morning and then 45 in the evening than it would be the better choice. There are a couple of reasons for this. First by working out twice you alway your body to replace some of the nutrients, creatine, carbs and other chemicals that make you muslces work (Doing one long workout just continues to deplete these.). Second, your body can start to rebuild some of the trama that you have caused in the first workout, allowing you to get just a little bit more out of your muscles. In the past I when have done in twice a day (working two body parts) I would focus on hitting my chest primarily in the first workout (ex. Chest and Triceps) while still hitting my triceps with an exercise or two. Then latter on when I would do the second one I would focus more on my triceps while still hitting my chest with another or two exercises to finish them off. I get much better results with two workouts. In the past I have gained more muscle weight doing this than just one long one.

to actually answer your question...

your body has growth and repair hormones that are released when cortisol levels are low and you are asleep.

working out twice in one day on the same body parts does NOT allow for substantial recovery of these muscles and hence you will be training a fatigued muscle which is not going to do much for you (in terms of hypertrophy)

"Also stating that muscle protein synthesis increases within a few hours after a bout of strenuous exercise and remains elevated for at least 24 hrs returning to normal at after approximately 72 hrs."

if you're goal is strength endurance than by all means go ahead, but trying to work a muscle when it is trying to repair itself is nonsensical in regards to bodybuilding.

If what I see does not amaze me, I am not looking hard enough.

The more you learn, the more you realize you don't know.
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your body has growth and repair hormones that are released when cortisol levels are low and you are asleep.

working out twice in one day on the same body parts does NOT allow for substantial recovery of these muscles and hence you will be training a fatigued muscle which is not going to do much for you (in terms of hypertrophy)

"Also stating that muscle protein synthesis increases within a few hours after a bout of strenuous exercise and remains elevated for at least 24 hrs returning to normal at after approximately 72 hrs."

if you're goal is strength endurance than by all means go ahead, but trying to work a muscle when it is trying to repair itself is nonsensical in regards to bodybuilding.

What is your opinion on doing two 45 minute workouts, but working different muscle groups? As for training a damaged muscle, I remember reading an article by Chad Waterbury about how "training through soreness=growth cuz that's how athletes train and they get hyooge sport specific muscles".

if you work out once for one and a half hours you still have time to show off your muscles and get some girls! if you work out twice for 45 minutes you don't have any days off and the only people, who see your muscles are the guys in the gym...

whats the difference between working out an hour and a half once a day vs 45 min twice??

is there any what soever?

its proven that level of cortisol (a catabolic hormone) raise after 45 min of training. Drinking gatorade or any other carbs drink during training raise insulin level that counter cortisol effects. So working 45 min twice a day is a good alternative

unless you are experienced and been working out for at least a few years, then 2x45 min sessions would be fine, but if not stick to one 45-50 minute session per day. fatigue will kick in as will overtraining.

its proven that level of cortisol (a catabolic hormone) raise after 45 min of training. Drinking gatorade or any other carbs drink during training raise insulin level that counter cortisol effects. So working 45 min twice a day is a good alternative

google science FTW!

If what I see does not amaze me, I am not looking hard enough.

The more you learn, the more you realize you don't know.
__________________
My Powerlifting Journal: http://forum.bodybuilding.com/showthread.php?p=189654831

find out what works for you

Body building and working out are partly about what works best for you. I cannot tell you what that is. If you have been working for very long than you know about DOMS and overtraining and some of the of terms of the gym. The one thing you need to be sure of is not to overtrain your body. If you feel you get a good workout in, in 50 minutes great and if it takes you a little longer than its alright. No two people are the same and you should pay close attention to what your body tells you while you work out, after, and during your recovery. Just experiment and listen to what your body tells you, it doesn't hurt to make sure your nutrition is solid either.